1. Field of the Invention
This invention relates to a predicting system continued to predict an inflow volume of rainwater, which is necessary to operate pumps arranged in a sewage treatment plant in order to drain rainwater in raining, or to control to open or close gates arranged in paths to temporary storing facilities for rainwater (storage basin, storing ducts, adjusting ponds and so on) in order to avoid flooding disasters.
2. Description of the Related Art
The sewage treatment plant not only treats sewage but also plays a role of preventing disasters caused by stormwater. Thus, the sewage treatment plant is an important facility in order to secure urban hygiene and environmental safety. Usually, rainwater is drained off from sewage ducts to a sea or a river via draining pumps arranged in a pump facility or a sewage treatment plant. Thus, it is important to determine the number of the draining pumps to be operated, based on an inflow volume of rainwater into the pump facility or the sewage treatment plant.
Recently, since residential areas have become denser and paved roads have spread, a greater part of rainwater has flown into the sewage ducts. Then, since the pumps have limitations of capacities for draining off the rainwater, temporary storing facilities for rainwater such as storing ducts or adjusting ponds have been provided more often. In the case of using the temporary storing facilities of rainwater, it is important to suitably control open apertures of respective gates to the storing facilities of rainwater.
In order to suitably determine the number of pumps to be operated and efficiently control the open apertures of the respective gates to the storing facilities of rainwater, it is desired to accurately predict an inflow volume of rainwater into the pump facility, the treatment plant or the storing facilities of rainfall and to use the predicted data for the determination and the control.
As the temporary storing facilities for rainwater have developed only recently, no prior art concerning the control of the gates is found. However, concerning the determination of the number of pumps to be operated, there are known two types, which are a type not using a prediction of an inflow volume of rainwater into the pump facility and another type using the prediction of the inflow volume of rainwater into the pump facility.
The type not using the prediction of the inflow volume of rainwater into the pump facility includes a method for determining the number of pumps to be operated based on measured data of rainfall and intuition of an operator of the pump facility, and a method for determining the number of pumps to be operated based on a water level measured by a water gauge arranged in a pump well of the pump facility.
The type using the prediction of the inflow volume of rainwater into the pump facility includes a method of measuring amounts of rainfall that has fallen by the present time by a plurality of rainfall gauges arranged on the ground and predicting the inflow volume of rainwater by using an RRL method. In addition, the type includes a method of constructing a prediction model by estimating parameters of an ARMAX model, which represents a relationship between the rainfall volume and the inflow volume of rainwater, by an ARMAX identification method and predicting the inflow volume of rainwater based on the prediction model. The type also includes a kinematic-wave method. Herein, the RRL method and the kinematic-wave method are called white-box-models. On the other hand, the ARMAX identification method is called a black-box-model.
The RRL method is a method for calculating the inflow volume of rainwater, which was developed by the England Road Laboratory. The RRL method is explained hereinafter.
In the RRL method, a duct chart (Sewer Network Diagram) is made wherein hydraulic features of ducts in an objective area, for example respective lengths, respective diameters and respective inclinations of the ducts, are written. Then, assuming that the whole duct chart is a single basin, a lowermost point of the basin is selected as a point p for calculating an inflow volume. Then, flow rates in main collecting ducts, open ducts and so on are calculated. Then, the so-called time-area curves are defined and written in such a manner that a time flowing between each two of neighboring curves of the rainwater toward the point p is equal to a time necessary to calculate an inflow volume of rainwater. Areas divided by the time-area curves are calculated as time-differentiating-areas Ai[m2].Thus, a time-area chart is made. The above operations are conducted manually.
Then, a rainfall curve (chart) is defined and written based on rainfall intensities Ii[mm/s] in the basin for respective unit times i for calculating the inflow volume. A flowing coefficient C that represents a flowing ratio is given as a fixed value defined from a using condition of the ground in the basin. A provisional inflow volume of rainwater Pi is calculated from the made rainfall curve and the made time-area chart, according to the following equation (1).                     Pi        =                              ∑                          k              =              1                        n                    ⁢                      {                          C              xc3x97                              I                                  i                  -                  k                  +                  l                                            xc3x97                              A                k                                      }                                              (        1        )            
In general, the rainwater generated by the rainfall does not immediately flow into the facility, but is temporarily stored in the ducts and flows into the facility after that. Thus, the inflow volume of rainwater is calculated by substituting the provisional inflow volume of rainwater Pi for an equation representing a relationship between the stored amount of rainwater and the inflow volume of rainwater. The equation representing the relationship between the stored amount of rainwater and the inflow volume of rainwater is explained as below.
S(t)=KQ(t)nxe2x80x83xe2x80x83(2)
(K, n: CONSTANTS OF THE BASIN)
                                                        ⅆ                              S                ⁡                                  (                  t                  )                                                                    ⅆ              t                                =                                    P              ⁡                              (                t                )                                      -                          Q              ⁡                              (                t                )                                                    ⁢                  
                ⁢                  (                                                                      S                  ⁢                                      :                                    ⁢                                      xe2x80x83                                    ⁢                  STORED                  ⁢                                      xe2x80x83                                    ⁢                                      AMOUNT                    ⁢                                          xe2x80x83                                        [                                          m                      3                                        ]                                                                                                                        P                  ⁢                                      :                                    ⁢                                      xe2x80x83                                    ⁢                  PROVISIONAL                  ⁢                                      xe2x80x83                                    ⁢                  INFLOW                  ⁢                                      xe2x80x83                                    ⁢                                      VOLUME                    ⁢                                          xe2x80x83                                        [                                                                  m                        3                                            ⁢                                              /                                            ⁢                      s                                        ]                                                                                                                        Q                  ⁢                                      :                                    ⁢                                      xe2x80x83                                    ⁢                  INFLOW                  ⁢                                      xe2x80x83                                    ⁢                                      VOLUME                    ⁢                                          xe2x80x83                                        [                                                                  m                        3                                            ⁢                                              /                                            ⁢                      s                                        ]                                                                                                          (        3        )            
The equation (2) is called a kinematics (motion) equation. The equation (3) is called a continuity equation. Usually, the following equation (4) which is obtained by differentiating the equation (3) is used for calculating the inflow volume of rainwater.                                           Q            i                    +                                    2                              Δ                ⁢                                  xe2x80x83                                ⁢                t                                      ⁢                          S              i                                      =                              (                          Pi              +              Pi              -              1                        )                    -                      Q                          i              -              1                                +                                    2                              Δ                ⁢                                  xe2x80x83                                ⁢                t                                      ⁢                                          S                                  i                  -                  1                                            ⁢                              
                            (                              Δ                ⁢                                  xe2x80x83                                ⁢                t                ⁢                                  :                                ⁢                                  xe2x80x83                                ⁢                differential                ⁢                                  xe2x80x83                                ⁢                time                            )                                                          (        4        )            
The inflow volume of rainwater calculated by the above manner is finally determined as an inflow volume of rainwater Qi of the point p for calculating the inflow volume of rainwater.
In addition, there is a modified RRL method wherein a point (view) of effective rainfall, wherein a pervious area and an impervious area is divided, is added to the RRL method. In the modified RRL method, the relationship between the stored amount of rainwater and the inflow volume of rainwater is modified with respect to the RRL method. Concerning the basic processes, the modified RRL method is similar to the RRL method. Furthermore, there is an expanded RRL method wherein the point of effective rainfall is modified with respect to the modified RRL method, and wherein points of introducing a function depending on a time and of dividing the basin are added to the modified RRL method.
Next, the ARMAX identification method is explained as below.
In the ARMAX method, a transfer function model as shown in FIG. 11 is defined as a function representing a relationship between the rainfall volume and the inflow volume of rainwater. In FIG. 11, u represents data of the rainfall volume, y represents data of the inflow volume of rainwater, and e represents a measurement error that can not be observed. In addition, the equations (5), (6) and (7) are satisfied.
A(z)=anzn+anxe2x88x921znxe2x88x921+. . . +a0xe2x80x83xe2x80x83(5)
B(z)=bmzm+bmxe2x88x921zmxe2x88x921+. . . +b0xe2x80x83xe2x80x83(6)
C(z)=clzl+clxe2x88x921zlxe2x88x921+. . . +c0xe2x80x83xe2x80x83(7)
Then, coefficient parameters in the equations (5) to (7) are determined by using some data of the rainfall volume and some data of the inflow volume of rainwater for a past time before a predicting time, for example by a least square method, in such a manner that the relationship between the rainfall volume and the inflow volume of rainwater among u to y in FIG. 11 may be nearest to a real relationship between them. The model shown in FIG. 11 using the determined parameters is determined as a predicting model.
Then, data of predicted rainfall-volume at a time when it is desired to predict are inputted into the predicting model to calculate (predict) the inflow volume of rainwater. A calculated (predicted) result by using the ARMAX model and an actual result are shown together in FIG. 12.
The described RRL method has following problems. That is, the duct chart, the time-area curves and time-area chart have to be made (written) for each basin, which needs much labor. In addition, besides the data of amount of the rainfall and the data of the inflow volume of rainwater for the past time, data about the ducts for making the duct chart for each basin and data about the using conditions on the ground for calculating the flowing coefficient C have to be collected, which needs more labor. A processing operation for incorporating the collected data into a processing system needs much labor. In addition, as the determination of the flowing coefficient C and so on may tend to be arbitrary, the accuracy of the prediction may be uncertain. The described modified RRL method and the described expanded RRL method also have the similar problems about determining the flowing coefficient C.
On the other hand, the ARMAX method does not need the labor that is needed by the RRL method. However, the accuracy of the prediction with the ARMAX model may be low because the ARMAX model does not reflect a non-linear phenomenon that is learned by experience. For example, an inflow volume of rainwater in hard raining or in light raining may be not proportional to the rainfall volume. In addition, in urban areas, there is a non-linearity wherein the inflow volume of rainwater increases rapidly as the rainfall volume increases. Furthermore, although the ARMAX model can be identified accurately when a white signal (noise) is inputted, it is uncertain that the ARMAX model may be identified accurately when the data of the rainfall volume and the data of the inflow volume of rainwater are inputted.
The object of this invention is to solve the above problems, that is, to provide a predicting system and a predicting method configured to predict an inflow volume of rainwater, which can predict the inflow volume of rainwater flowing into an objective facility with a high accuracy even if a non-linear relationship may happen between a rainfall volume and the inflow volume of rainwater.
In order to achieve the object, the present invention is featured by the character that a predicting system configured to predict an inflow volume of rainwater, includes:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
a rainfall volume predicting unit for predicting a rainfall volume in a future,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
a non-linear model having a Neural-Network model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the non-linear model, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume in the future predicted by the rainfall volume predicting unit, according to the non-linear model determined by the model identification unit.
In addition, the present invention is featured by the character that a method for predicting an inflow volume of rainwater flowing into an objective facility by using a predicting system configured to predict an inflow volume of rainwater, including:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
a rainfall volume predicting unit for predicting a rainfall volume in a future,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
a non-linear model having a Neural-Network model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the non-linear model, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume in the future predicted by the rainfall volume predicting unit, according to the non-linear model determined by the model identification unit; includes:
a step of determining the degree and the coefficient parameters of the non-linear model by the parameter determining part, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
a step of predicting the inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume in the future predicted by the rainfall volume predicting unit, according to the non-linear model determined by the model identification unit, by the inflow-volume predicting unit.
According to the features, the inflow volume of rainwater corresponding to the rainfall volume in the future is predicted by using the non-linear model having the Neural-Network model, whose degree and whose coefficient parameters are determined by the parameter determining part based on the rainfall volume that has fallen by the present time and the inflow volume of rainwater that has flown into the objective facility by the present time. Thus, the inflow volume of rainwater can be predicted with a high accuracy, even if a non-linear relationship may happen between the rainfall volume and the inflow volume of rainwater.
Preferably, the rainfall volume measuring unit is adapted to respectively measure amounts of rainfall that have fallen for respective unit times by the present time, the inflow-volume measuring unit is adapted to respectively measure inflow volumes of rainwater that have flown into the objective facility for respective unit times by the present time, and the parameter determining part is adapted to determine the degree and the coefficient parameters of the non-linear model, based on a plurality of data of the amounts of rainfall that have fallen for the respective unit times by the present time measured by the rainfall volume measuring unit and a plurality of data of the inflow volumes of rainwater that have flown into the objective facility for the respective unit times by the present time measured by the inflow-volume measuring unit.
Preferably, the rainfall volume measuring unit is connected to a rainfall volume data picking-up unit which is adapted to pick up only necessary data of the amounts of rainfall, from the plurality of data of the amounts of rainfall that have fallen for the respective unit times by the present time measured by the rainfall volume measuring unit, and the inflow-volume measuring unit is connected to an inflow-volume data picking up unit which is adapted to pick up only data of the inflow volumes of rainwater corresponding to the picked up data of the amounts of rainfall, from the plurality of data of the inflow volumes of rainwater that have flown into the objective facility for the respective unit times by the present time measured by the inflow-volume measuring unit.
Preferably, the model identification unit has an efficient-rainfall-volume calculating part for calculating a contributing rainfall-volume to an inflow volume of rainwater flowing into the objective facility, based on a preceding rainfall, and the parameter determining part is adapted to determine the degree and the coefficient parameters of the non-linear model, based on the contributing rainfall-volume calculated by the efficient-rainfall-volume calculating part and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit.
Preferably, at least one of the rainfall volume measuring unit and the inflow-volume measuring unit has a noise reducing part.
Preferably, a plurality of rainfall volume measuring units are arranged in an area covered by the objective facility, for measuring a plurality of data of amounts of rainfall, the rainfall volume predicting unit is adapted to predict a plurality of data of amounts of rainfall in a future, said plurality of data of the amounts of rainfall corresponding to the plurality of rainfall volume measuring units respectively, the non-linear model is a model into which a plurality of data are inputted, the parameter determining part is adapted to determine the degree and the coefficient parameters of the non-linear model into which the plurality of data are inputted, based on the plurality of data of the amounts of rainfall measured by the plurality of rainfall volume measuring units and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and the inflow-volume predicting unit is adapted to predict the inflow volume of rainwater flowing into the objective facility in the future, based on the plurality data of the amounts of rainfall in the future predicted by the rainfall volume predicting unit, according to the non-linear model determined by the model identification unit.
Preferably, the parameter defining part has a program constructed by an algorithm using a least square method.
In addition, the present invention is featured by the character that a predicting system configured to predict an inflow volume of rainwater, includes:
a predicting system configured to predict an inflow volume of rainwater, comprising:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
a rainfall volume predicting unit for predicting a rainfall volume in a future,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
an efficient-rainfall-volume calculating part for calculating a contributing rainfall-volume to an inflow volume of rainwater flowing into the objective facility, based on a preceding rainfall and a non-linear model,
a linear model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the linear model, based on the contributing rainfall-volume calculated by the efficient-rainfall-volume calculating part and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume in the future predicted by the rainfall volume predicting unit, according to the linear model determined by the model identification unit.
In addition, the present invention is featured by the character that a method for predicting an inflow volume of rainwater flowing into an objective facility by using a predicting system configured to predict an inflow volume of rainwater, including:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
a rainfall volume predicting unit for predicting a rainfall volume in a future,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
an efficient-rainfall-volume calculating part for calculating a contributing rainfall-volume to an inflow volume of rainwater flowing into the objective facility, based on a preceding rainfall and a non-linear model,
a linear model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the linear model, based on the contributing rainfall-volume calculated by the efficient-rainfall-volume calculating part and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume in the future predicted by the rainfall volume predicting unit, according to the linear model determined by the model identification unit; includes:
a step of calculating the contributing rainfall-volume to the inflow volume of rainwater flowing into the objective facility based on the preceding rainfall and the non-linear model, by the efficient-rainfall-volume calculating part,
a step of determining the degree and the coefficient parameters of the linear model, based on the contributing rainfall-volume calculated by the efficient-rainfall-volume calculating part and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, by the parameter determining part, and
a step of predicting the inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume in the future predicted by the rainfall volume predicting unit, according to the linear model determined by the model identification unit, by the inflow-volume predicting unit.
According to the features, the efficient-rainfall-volume calculating part calculates the contributing rainfall-volume to the inflow volume of rainwater based on the preceding rainfall and the non-linear model, the parameter determining part determines the degree and the coefficient parameters of the linear model based on the contributing rainfall-volume and the inflow volume of rainwater, and the inflow volume of rainwater corresponding to the rainfall volume in the future is predicted by using the linear model. Thus, the inflow volume of rainwater flowing into the objective facility can be predicted with a high accuracy.
Preferably, the parameter defining part has a program constructed by an algorithm using a least square method.
In addition, the present invention is featured by the character that a predicting system configured to predict an inflow volume of rainwater, includes:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
a non-linear model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the non-linear model, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit, according to the non-linear model determined by the model identification unit.
In addition, the present invention is featured by the character that a method for predicting an inflow volume of rainwater flowing into an objective facility by using a predicting system configured to predict an inflow volume of rainwater, including:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
a non-linear model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the non-linear model, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit, according to the non-linear model determined by the model identification unit; includes:
a step of determining the degree and the coefficient parameters of the non-linear model, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, by the parameter determining part, and
a step of predicting the inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit, according to the non-linear model determined by the model identification unit, by the inflow-volume predicting unit.
According to the features, the inflow volume of rainwater in the future is predicted from the rainfall volume that has fallen by the present time by using the non-linear model, whose degree and whose coefficient parameters are determined by the parameter determining part based on the rainfall volume that has fallen by the present time and the inflow volume of rainwater that has flown into the objective facility by the present time. Thus, the inflow volume of rainwater in near future can be easily predicted with a high accuracy.
Preferably, a plurality of rainfall volume measuring units are arranged in an area covered by the objective facility, for measuring a plurality of data of amounts of rainfall, the non-linear model is a model into which a plurality of data are inputted, the parameter determining part is adapted to determine the degree and the coefficient parameters of the non-linear model into which the plurality of data are inputted, based on the plurality of data of the amounts of rainfall measured by the plurality of rainfall volume measuring units and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and the inflow-volume predicting unit is adapted to predict the inflow volume of rainwater flowing into the objective facility in the future, based on the plurality of data of the amounts of rainfall that has fallen by the present time measured by the plurality of rainfall volume measuring units, according to the non-linear model determined by the model identification unit.
In addition, the present invention is featured by the character that a predicting system configured to predict an inflow volume of rainwater, includes:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
an efficient-rainfall-volume calculating part for calculating a contributing rainfall-volume to an inflow volume of rainwater flowing into the objective facility, based on a preceding rainfall and a non-linear model,
a linear model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the linear model, based on the contributing rainfall-volume calculated by the efficient-rainfall-volume calculating part and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit, according to the linear model determined by the model identification unit.
In addition, the present invention is featured by the character that a method for predicting an inflow volume of rainwater flowing into an objective facility by using a predicting system configured to predict an inflow volume of rainwater, including:
a rainfall volume measuring unit for measuring a rainfall volume that has fallen by a present time,
an inflow-volume measuring unit for measuring an inflow volume of rainwater that has flown into an objective facility by the present time,
a model identification unit having
an efficient-rainfall-volume calculating part for calculating a contributing rainfall-volume to an inflow volume of rainwater flowing into the objective facility, based on a preceding rainfall and a non-linear model,
a linear model for calculating an inflow volume of rainwater from a rainfall volume, and
a parameter determining part for determining a degree and coefficient parameters of the linear model, based on the contributing rainfall-volume calculated by the efficient-rainfall-volume calculating part and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, and
an inflow-volume predicting unit for predicting an inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit, according to the linear model determined by the model identification unit; includes:
a step of calculating the contributing rainfall-volume to the inflow volume of rainwater flowing into the objective facility based on the preceding rainfall and the non-linear model, by the efficient-rainfall-volume calculating part,
a step of determining the degree and the coefficient parameters of the linear model, based on the contributing rainfall-volume calculated by the efficient-rainfall-volume calculating part and the inflow volume of rainwater that has flown into the objective facility by the present time measured by the inflow-volume measuring unit, by the parameter determining part, and
a step of predicting the inflow volume of rainwater flowing into the objective facility in the future, based on the rainfall volume that has fallen by the present time measured by the rainfall volume measuring unit, according to the linear model determined by the model identification unit, by the inflow-volume predicting unit.
According to the features, the efficient-rainfall-volume calculating part calculates the contributing rainfall-volume to the inflow volume of rainwater based on the preceding rainfall and the non-linear model, the parameter determining part determines the degree and the coefficient parameters of the linear model based on the contributing rainfall-volume and the inflow volume of rainwater, and the inflow volume of rainwater in the future is predicted from the rainfall volume that has fallen by the present time by using the linear model. Thus, the inflow volume of rainwater in near future can be easily predicted with a high accuracy.